Basal and insulin-mediated protein, carbohydrate, and lipid metabolism during HBss and to ascertain how these alterations affect energy expenditure. Identify alterations in basal protein, glucose, and lipid metabolism during HbSS and to ascertain how these alterations affect energy expenditure. To determine the impact of HbSS on insulin-mediated protein, glucose, and lipid metabolism and energy expenditure and to assess the contribution of hepatic vs. peripheral insulin sensitivity and responsiveness to any observed changes in metabolism. Evaluate the impact of HbSS on insulin-mediated substrate (protein, carbohydrate, and lipid) oxidation and energy expenditure.